55 



we learn frora the great work of Sir R. Murchison and M. de Verneuil, in the Ural motra- 

 tains, thick masses of strala are in some places overturned, and, on the flanks of the latter 

 mountains, the order of superposition is thus sometimes inverted. But such cases cannot 

 justifiy us in supposing that in a similar convulsion on a transcendent scale the Himalayas 

 originated. The metamorphic theory might get rid of the difficulty if it could be shown 

 that the gneiss and other rocks resting on the new red sandstone were really more modern 

 sedimentary rocks! (1) Until we possess further light we seem justified in considering that the 

 researches and conclusions of Captain Herbert tend to prove that the passage of gneiss into 

 granite or the reverse may be determined simply by the variable proporlions of mica and the 

 conditions of crystallization from a common state of fluidity or viscidity. A portion of the 

 Himalayas has more recently been examined by Dr. M acGlelland , and he declares positively 

 that the granite is stratified, the strata being nearly vertical and appearing to be composed 

 of nodules around which concentric layers are wrapped. He states also that the gneiss rest» 

 on the granite in conformable strata, and that the two rocks pass insensibly into each other (2). 

 The metamorphic theory starts on a basis of fact and is demonstrably true up to a cer- 

 tain limit. But when applied to mountain masses of enormous thickness we leave 

 that limit far behind. The conversion of the Himalayas from soft sedimentary into 

 crystalline matter cannot be explained by the plutonic action of granite on known aqueous 

 rocks, even where it has pervaded them to the thickness of a few hundred yards. If the 

 Himalayas were metamorphosed, the process must have been different, or plutonic 

 influences must have been in operation of far greater potency, and having in some respects 

 a different mode of action. There is an unsatisfactory want of definiteness about the meta- 

 morphic theory even when expounded by its great advocate M. Lyell. If the ingredients of 

 gneiss, were originally arranged as we find them at present, then it only differs from the 

 Wernerian theory in substituting a posteriour for an aboriginal consolidation , and places 

 gneiss on the same footing with any of the secondary or tertiary sandstones that have as- 

 sumed a stony texture si nee they were depositcd from water. On the other hand if it takes 

 a bolder grasp of the difficulty and asserts that the whole structure of the rock, the regular 

 form of its crystals, and the separation of those of different species into alternate laminae, 

 are due to the mass having been melted into a viscid state and subjected to crystalliz,ation 

 de novo , it appears to corae so close to direct plutonic formation that it is not easy to see 

 where room is to be found for a vast metamorphic laboratory on the confines of the latter. 

 Its advocates have probably seen and shrunk from the difficulty of defining the conditions 



(1) Dr. BtcKiABD estimates Ihe thickness of all the European stratified rocks including the pritnary at ten miles. 

 Sridgetealer Treatite, vol. 2 , p. 39. 



(2) M. Caldeb descrihes the granite in the district of Tennivelly in Southern India as »rising above thesurfaee 

 in remarUably globular concretions and in perfect ly stratified masses'''' , fortuin» low detached hills near Palem- 

 coatta the strata of which dip at au angle of about 45o to the SW. (Buewsters Edinlurgh Journal of Science , 

 vol. X , p. 138). Other writers on the geology of India mention Ihe occurrence of granite in many places with 

 a similar appearance. Himfioi.dt in his work on Central Asia descriles the remarkahle structure of the granite 

 sarrounding the mass of the Allai. At Kolyvan a large grained granite is »regularly stratified". 



